Domestic tumble dryers that employ compression heat pumps consume 50% less primary energy than those equipped with electric resistance heaters. However, examinations of compression heat pumps from an ecological and safety-related standpoint raise questions about the refrigerants utilized in the process. To meet the growing concern about the high global warming potential of certain chemical compounds that are typically found in refrigerants, it is imperative to develop a substitute for compression heat pumps.
A conventional condensation tumble dryer includes a closed process air circuit, in which the enclosed air circulates inside the tumble dryer. Cool and dry process air is initially heated and then passed through the drum which spins wet clothes. During the subsequent vaporization process, moisture is removed from the load and the humid air eventually leaves the drum at a moderate temperature. Then, the humid air is cooled, the moisture is condensed and removed, and the air is heated up again, restarting the cycle. In a conventional heat pump, the heating and cooling takes places in the evaporator and condenser, respectively.
In addition to the use of electric resistance heaters and compression heat pumps, some designs using thermoelectric modules in tumble dryers have been proposed. However, there is an ongoing need for efficient alternatives to conventional heat pumps and electric resistance heaters in tumble dryers.
Further, there is an ongoing need for efficient techniques for heating and cooling in a wide variety of fields.